The present invention relates to a head mounted display with which one is capable of observing a pictorial image of an image, a moving picture and the like made by a computer through directly focusing onto retina by arranging a micro-display attached on glasses or the like in front of eyes. More particularly, the present invention relates to a head mounted display with which one is capable of observing under highly natural state by resolving a feeling of wrongness in the case where one of the eyes observes the faraway outside world while the other observes the head mounted display or in the case where the identical eye observes the display and the faraway, alternately. Here, a head mounted display does not mean only a display which is directly mounted on the head, but also a display which directly irritates an image into an eye of a person who is mounted with the head mounted display and which is not seen from the others except the person who is mounted with it such as in the case where the display is mounted on glasses or a hat.
Recently, miniaturization of electronic devices is proceeded, a head mounted display (HMD), such as a wearable computer has been developed, which arranges pictorial images such as an image of computer, of a game and of a movie picture and the like in front of eyes of a human, directly projects the images onto retina and making it allow to be seen by only one person. As for such devices, a device is considered to be used such that a small micro-display scaled on the order of a square of millimeter units is arranged in front of one of eyes while the other eye is capable of observing the outside world in a free and ordinary state.
Thus, one has to see objects having largely different focal distances at each time of the moments in the case where left and right eyes or even the identical eye see the head mounted display and the outside world alternately, if it is in a state where it is not natural that one of the eyes observes the display while the other eye is focused on the outside world, or in a state where when the eye observing the head mounted display looks aside, comes to see the outside world. Since human eyes have the ability to correspond the situation by changing focusing image location to retina by the action of lens in the case where one sees objects having different distances from the eyes which are proximal and distal, one can follow to see a display and the outside world alternately. However, such following movements take some time to some degree. In addition, if one observes objects having different focal distances approximately at the same time or repeatedly, such as in the case where respective eye sees objects having different distances from the eyes or in the case where one observes the display and the outside world alternately, the eyes tends to be very easily tired and it is very much unpleasant to wear a head mounted display for a long time.
Furthermore, if a head mounted display is made in a state of see-through and one is capable of seeing the outside world behind a displaying image of the head mounted display, even human eyes cannot follow the situation that one has to see and recognize both of the display and the outside world.
The present invention is performed in consideration of such situations and an object of the present invention is to provide a head mounted display with which one is capable of observing almost without occurring the fatigue of the eyes, even in the case where one sees and recognizes both of the outside world and a head mounted display approximately at the same time.
Another object of the present invention is to provide a head mounted display capable of automatically switching into a power saving mode after certain time period when one does not observe the head mounted display by slightly looking aside or somehow even when the head mounted display is arranged in from the eyes.
A head mounted display according to the present invention comprises a micro-display, a condenser lens focusing an image of the micro-display onto retina of human eyes, a reflected light detection means for detecting brightness of the reflected light which is reflected on retina of human eye and location adjusting means for adjusting the relationship of locations of the micro-display and the condenser lens so as to optimizing the focusing image on the retina by the brightness of the reflected light. It should be noted that xe2x80x9coptimizing the focusing imagexe2x80x9d means that making being in focus or making shift of an image in a lateral direction being in focus and focusing an image onto retina in a state of being easily recognizable.
By constructing a device into this structure, nevertheless the situation of lens of eye, the location relationship between the head mounted display and the condenser lens is adjusted so that a focusing image on retina is automatically optimized. Therefore, if one observes a head mounted display in a state of observing the faraway outside world, the location relationship between the head mounted display and the condenser lens is adjusted so that the most suitable focusing image on retina in that state is obtained. Moreover, if one observes only the head mounted display and observer""s eye is adjusted by the action of lens of an eye so that the location of the display is focused, the location of the condenser lens is automatically adjusted so that the focus of the image of the display is formed onto retina in the state of its lens of an eye. Specifically, in order to adjust a focus of an image of the display corresponding to the state of lens of an eye before the adjustment of the action of lens of an eye, one can observe an image of the display at the same time without any feeling of wrongness in the state of an eye observing the outside world.
The reflected light detection means comprises a block of the light emitting section and the light receiving section which are formed in a portion of the display section of the micro-display. It will be good to have such structures that the block is means for detecting a reflected light reflected by the retina to which the light is emitted by the light emitting section or that a half mirror is provided between the micro-display and the lens and a detector for detecting the reflected light reflected by the half mirror is provided. It should be noted that the block of the light emitting section and the light receiving section is formed so that it is contained within the beam of the beam waist portion where the beam of the reflected light is most narrowed.
Further comprising a frequency modulating means which modulates a light of the light emitting section by alternating current, and a band pass filter selecting a detecting signal of the reflected light of the modulated light, and thereby can monitor the accurate intensity of the reflected light which is not influenced by noises with a small amount of emitting light.
Moreover, it is preferable that the reflected light detecting means has detection sections of two colors, which are at least different at wavelengths on the micro-display and adjusts the forgoing relationship to the most suitable location by the correlation of the detecting sections of at least two colors, or has detecting sections of the reflected light in at least two places which are located at different locations on the micro-display, and adjusts the forgoing relationship to the most suitable location by the correlation of the detecting sections of at least two places, thereby immediately determining whether forward or backward adjustment should be taken or whether left or right adjustment should be taken and adjustment to the accurate location can be carried out more rapidly.
By constituting the micro-display so that the display screen (pixels) is provided on the semiconductor substrate in which an integrated circuit is formed, the light receiving section of the reflected light detecting means can be formed directly on the substrate, a circuit for comparing the reflected lights, a driving circuit and the like can be formed on the substrate, therefore, it can be constituted in a three dimensional shape, is easily formed to be extremely compact and is desirable.
By providing an automatic switch means which makes at least the micro-display or the computer main body be power saving mode by detecting the output of the reflected light detecting means, and by turning one""s eyes away from the display during certain time period, since the absence of reflected light by retina can be detected and made it be power saving mode, consumption of the power of portable devices can be suppressed and it is especially preferable to use as a portable device.